It is often difficult to decide where nets go when the need for nets far exceeds the quantity we can fund.
Should 20,000 nets go to one country or 10,000 each to two countries? The dilemma is the same whatever the number of nets involved. Some people somewhere will remain unprotected from malaria whatever the decision.
The choice is particularly stark when deciding whether to focus on those most at risk from malaria—children under five years old and pregnant women—or instead to achieve universal coverage, which means every sleeping space is covered in a (smaller) area.
A real example: There are 500 nets in total available for five villages. Each village contains 1,000 people, among whom are 100 pregnant women and children under five. Do you protect all the under fives and pregnant women in all five villages or blanket cover one village, given two people sleep under each net?
Each method has its benefits.
The logic of protecting the most vulnerable is obvious: those most likely to contract malaria due to a less well-developed immune system (under fives) or weakened immune system (pregnant women) should be protected first. Their need is greatest and so they deserve our attention first.
The argument for universal coverage centres on the 'mass-effect' that occurs when 60% or more of sleeping spaces in a given area are covered. In such a circumstance, malaria rates fall dramatically because the pregnant female malaria-carrying mosquito population is denied its nightly blood meal. If these mosquitoes do not feed for 10-12 days they cannot reproduce. Fewer mosquitoes means fewer ways to get infected, which reduces the spread of malaria among net-users and non-net-users alike (see related links).
The advantages of universal coverage come not only from preventing the pregnant female mosquito feeding, but also from the involvement and engagement of an entire community in malaria prevention. It can have a dramatic effect with malaria case rates falling precipitously.
There is no one answer.
In recent years, the move has been to universal coverage given the often dramatic effect on an entire community. The intention, using the example above, would then be to come back to the other villages as soon as possible and universally protect them too. While there are not enough funds for nets this is not always possible. In the meantime, difficult choices remain.
Relevant links